"1. From the home menu, tap the settings icon (Grey icon with a couple of gears in it).

2. Tap on the "General" settings button.

3. From the "General" settings menu, choose the "Passcode Lock" item.

4. Tap the "Turn Passcode On" option at the top of the menu or enter your current passcode if you already have a passcode enabled.

5. Set the "Require Password" option to "Immediately" unless you wish to have a longer window of time before it is required. This is where you have the chance to balance security versus usability. You could create a longer passcode and set a longer window of time before it's required so you won't be constantly entering it or you could create a shorter passcode and require it immediately. Either choice has it's pros and cons, it just depends on what level of security vs. convenience you are willing to accept.

6. Change the "Simple Passcode" to the "OFF" position. This will enable the complex passcode option.

7. Enter your current 4-digit passcode if prompted.

8. Type in your new complex passcode when prompted and tap the "Next" button.

9. Type in your new complex passcode a second time to confirm it and tap the "Done" button.

10. Press the home button and then press the wake/sleep button to test out your new passcode. If you messed something up or lose your passcode check out this article on how to get back into your iPhone from a device backup."

It’s always tough to balance convenience with security. You can change so that the passcode is longer and more complex. Go to SETTINGS>GENERAL>PASSCODE LOCK. You should see an option for “Simple Passcode.” Switch that off, and you should be able to enter a passcode with more characters.